1. Field of the Invention
The present invention relates to a remote control toy car and, more particularly, to a dual-gearshift forward backward control mechanism for a remote control toy car.
2. Description of the Related Art
Regular gasoline engine remote control toy cars commonly use a transmission mechanism to increase the torque. However, because the transmission mechanism of a conventional gasoline engine remote control toy car provides only one transmission mode, it is less efficient to accelerate the speed, and the torsion cannot be increased during low speed. In order to eliminate these problems, dual-gearshift position transmission mechanisms are developed. However, prior art dual-gearshift position transmission mechanisms are commonly heavy, complicated, and expensive. Furthermore, the parts of the prior art high-precision dual-gearshift position transmission mechanisms wear quickly with use.
Further, regular gasoline engine remote control toy cars can be controlled to move forwards as well as backwards. However, the forward transmission and the backward transmission are controlled by two separated systems, i.e., when moving the toy car forwards, the user must start the forward transmission system to drive the toy car forwards; when moving the toy car backwards, the user must stop the forward transmission system and then start the backward transmission system. This forward backward transmission design is complicated, consumes much gasoline, and requires much installation space.
Like real cars, the wheels at the inner side and the wheels at the outer side have different speed of revolution when going round corners. In order to balance the speed between the wheels at the inner side and the wheels at the outer side when going round corners, a speed differential assembly shall be installed. However, because the forward transmission mechanism, the backward transmission mechanism, and the differential assembly are separated mechanisms, they cannot be installed in a common housing. Therefore, prior art gasoline remote control toy cars are commonly heavy and expensive.
The present invention has been accomplished to provide a dual-gearshift forward backward control mechanism for remote control toy car, which eliminates the aforesaid drawbacks. It is one object of the present invention to provide a dual-gearshift forward backward control mechanism for remote control toy car, which combines a two-step gearshift control mechanism and a forward backward control mechanism into a compact assembly that requires less chassis installation space. It is another object of the present invention to provide a dual-gearshift forward backward control mechanism for remote control toy car, which is inexpensive to manufacture and durable in use. To achieve these and other objects of the present invention, the dual-gearshift forward backward control mechanism for remote control toy car comprises an output shaft, the output shaft having a polygonal middle section; a switching gear mounted on the polygonal middle section of the output shaft for synchronous rotation with the output shaft and axially moved along the polygonal middle section between a first position and a second position; a first gear mounted on the output shaft, the first gear comprising an annular groove in one side thereof and a plurality of protruding blocks suspended in the annular groove; a second gear mounted on the output shaft, the second gear comprising a shoulder disposed at one side thereof and fitted into the annular groove of the first gear, an inner gear disposed in an opposite side thereof and adapted to engage the switching gear when the switching gear shifted to the first position, a swivel block pivoted to the shoulder, a spring mounted in the shoulder and supporting the swivel block in a non-operative position where the swivel block is not in engagement with the first gear, the swivel block being forced radially outwards by a centrifugal force into engagement with the protruded blocks of the first gear when the revolving speed of the second gear reached a predetermined level; a third gear mounted on the output shaft, the third gear comprising an inner gear adapted to mesh with the switching gear when the switching gear shifted to the second position; a center shaft, the center shaft having a transmission gear fixedly mounted thereon and meshed with the first gear; a first idle gear mounted on the center shaft, the first idle gear comprising a first gear portion meshed with the outer gear of the second gear and a second gear portion; a one-way axle bearing supported between the first idle gear and the center shaft; a second idle gear mounted on an axle for two-way synchronous rotation with the axle and adapted to engage the second gear portion of the first idle gear and the outer gear of the third gear; a driven gear fixedly fastened to the first gear; and an engine, the engine having a pinion fixedly provided at an output shaft thereof and meshed with the driven gear.